Effects of Fish Oil on Growth Performance and Carcass Characteristics of Broiler Chicks Fed a Low-protein Diet

Four hundred fifty, one-day-old broiler chickens were used in the study. The experiment was conducted in a 2 x 3 factorial arrangement with two dietary crude protein (CP) level (21 & 19% for grower & finisher phases, respectively) and 10% diluted CP (18.9 & 17.1 for grower & finisher phases, respectively) and three levels of fish oil inclusion (either 0, 2 or 4%). Weight gain of broiler chickens decreased by fish oil inclusion (P<0.05). A 10% reduction in dietary CP level decreased the weight gain (P<0.05) of chickens but didn't affect the feed intake. Feed conversion ratio of chicks fed the crude protein diluted diets was higher (P<0.05) than chicks fed recommended CP level. Abdominal fat pad weight was not affected by different diets. Fish oil inclusion at 4% level increased the thigh, breast, liver and small intestine weights as a percent of live weight (P<0.05). Reduction in dietary crude protein level, increased the breast ether extract concentration (P<0.05). The chicks fed diets containing 4% fish oil (FO) had a significantly lower ether extract in breast, but a higher ether extract concentration in thigh (P<0.05). There was no significant interaction between experimental factors indicating that the dietary crude protein level and polyunsaturated fatty acids type act independently on performance traits and carcass fat concentration.